DENVER (KDVR) — The Denver and Colorado departments of public health and environment have confirmed a second case of measles in Denver traced back to the first Denver case.

This is the fourth case reported in Colorado, with the other two being in Pagosa Springs and Pueblo. The new Denver case is an adult who had household contact with the baby diagnosed with measles in Denver earlier this month.

DDPHE said the adult has been in quarantine during their infectious period, and the department determined there is “no risk of measles to the general public from this new case.”

Since measles is highly contagious, the department advises any unvaccinated person to quarantine if they have the virus.

The department also said the MMR vaccine is safe and effective; two doses of the vaccine are about 97% effective in preventing measles.